Aum is the most powerful of all mantras. It is good to chant Aum seven or more times before and after each meditation. Chanting "Aum" puts you in harmony with the vibration of Eternity. "Aum" opens the gateway to the infinite highway of light.
I don't really regret much. I know there are things that I've done that have been wrong, and wish I could do over again, but I feel it's all made me who I am today, and I'm very thankful for that.